While I was in the U.S. Army stationed in Germany in the 80's I visited East and West Berlin before the fall of the USSR and after. Here are a couple pictures that I've found online that are good representations of what I saw in Alexander Platz, East Berlin.
Before the fall:
After the fall:
What struck me the most before:
Everything was grey. Very little color. Quiet. No loud voices. No crowds. People would look at me out of the corner of their eyes...but nobody would speak to me.
Complete opposite. Children, young people, adults laughing, smiling, talking...even to me. Color everywhere.